[0001] The invention generally pertains to intra-lumenal medical devices, such as guidewires,
catheters or the like, wherein in use, they are inserted into vascular lumens or other
body lumens for treatment and diagnosis.
[0002] A wide variety of medical devices have been developed for intraluminal, especially
intracorporeal, use. Elongated medical devices are commonly used to facilitate navigation
through and/or treatment within the anatomy of a patient. Because the anatomy of a
patient may be tortuous, it is desirable to combine a number of performance features
in such devices. For example, it is sometimes desirable that the device have a relatively
high level of pushability and torqueability, particularly near its proximal end. It
is also sometimes desirable that a device be relatively flexible, particularly near
its distal end. A number of different elongated medical device structures and assemblies
are known, each having certain advantages and disadvantages.
[0003] WO 98/58697 discloses a variable stiffness angioplasty guidewire. An angioplasty guidewire includes
a proximal shaft formed with an axial passage and a variable stiffness intermediate
section extending axially from the tubular shaft and having a corridor aligned axially
with the passage and terminating at a distal joint. The intermediate section comprises
a plurality of stiffening elements. A core element is slidably disposed axially through
the passage and includes a distal end projecting into the corridor and attached to
the distal joint while a flexible distal tip is mounted to the end of the intermediate
portion and projects axially-therefrom.
[0004] GB 1 119 158 discloses a spring guide for use in internal vascular manipulations. The spring guide
is formed from a coiled wire having, when straight, at least one curvable portion
wherein adjacent coils are contiguous to each other along one side of the coiled wire
and spaced from each other along the opposite side thereof. A core wire is generally
either permanently or releasably secured at the distal tip of the spring guide, the
core wire tip being provided with a cap. The spring guide may be incorporated in catheters
to mechanically distend a portion thereof.
[0005] However, there is an ongoing need to provide alternative elongated medical device
structures and assemblies.
[0006] The invention provides several alternative designs of alternative medical device
structures and assemblies as described in claim 1.
[0007] Accordingly, an example embodiment of the invention can be found in a medical device
that includes a coil having a longitudinal axis and a radial axis orthogonal to the
longitudinal axis, formed from a wire. The wire includes a cross-section with a centroid,
a moment of inertia with respect to an axis running through the centroid and parallel
to the longitudinal axis of the coil, and a moment of inertia with respect to an axis
running through the centroid and parallel to the radial axis of the coil. The moment
of inertia with respect to an axis running through the centroid and parallel to the
longitudinal axis of the coil is greater than the moment of inertia with respect to
an axis running through the centroid and parallel to the radial axis of the coil.
.
[0008] The medical device that includes a coil having a longitudinal axis and a radial axis
orthogonal to the longitudinal axis. The coil is formed from a composite wire that
includes a cross-section with a centroid, a wire longitudinal axis parallel to the
coil longitudinal axis and a wire radial axis parallel to the coil radial axis, a
first material having a first Young's Modulus at the centroid, and a second material
having a second Young's Modulus further away from the centroid along the wire radial
axis. The second Young's Modulus is greater than the first Young's Modulus.
[0009] The device further includes an elongated shaft including a proximal region having
a first outer diameter and a distal re ion having a second outer diameter that is
smaller than the first outer diameter and the coil member is connected to the elongated
shaft at the proximal region and extending from the proximal region over the distal
region. The coil member has an inner diameter that is greater than the second outer
diameter. The coil has a longitudinal axis and a radial axis orthogonal to the longitudinal
axis. The coil is formed from a wire that includes a cross-section with a centroid,
a moment of inertia with respect to an axis running through the centroid and parallel
to the longitudinal axis of the coil; and a moment of inertia with respect to an axis
running through the centroid and parallel to the radial axis of the coil. The moment
of inertia with respect to an axis running through the centroid and parallel to the
longitudinal axis of the coil is greater than the moment of inertia with respect to
an axis running through the centroid and parallel to the radial axis of the coil.
[0010] The above summary of some embodiments is not intended to describe each disclosed
embodiment or every implementation of the present invention. The Figures, and detailed
description which follow more particularly exemplify these embodiments.
[0011] The invention may be more completely understood in consideration of the following
detailed description of various embodiments of the invention in connection with the
accompanying drawings, in which:
Figure 1 is a perspective view of an example coil, incorporated into an elongate medical
device;
Figure 2 is a partial side elevation view of an example medical device coil;
Figure 3 is a longitudinal cross-sectional view of the example coil of Figure 2;
Figure 4 is a cross-sectional view of an example wire forming a coil;
Figure 5 is a cross-sectional view of an example wire forming a coil;
Figure 6 is a cross-sectional view of an example wire forming a coil;
Figure 7 is a cross-sectional view of an example wire forming a coil;
Figure 8 is a cross-sectional view of an example coil co-wound with a second coil;
Figure 9 is a cross-sectional view of an example guidewire with a coil;
Figure 10 is a cross-sectional view of an alternative example of a guidewire; and
Figure 11 is a cross-sectional view of an alternative guidewire with a coil.
[0012] While the invention is amenable to various modifications and alternative forms, specifics
thereof have been shown by way of example in the drawings and will be described in
detail. It should be understood, however, that the intention is not to limit the invention
to the particular embodiments described. On the contrary, the intention is to cover
all modifications, equivalents, and alternatives falling within the scope of the invention.
[0013] For the following defined terms, these definitions shall be applied, unless a different
definition is given in the claims or elsewhere in this specification.
[0014] All numeric values are herein assumed to be modified by the term "about," whether
or not explicitly indicated. The term "about" generally refers to a range of numbers
that one of skill in the art would consider equivalent to the recited value (i.e.,
having the same function or result). In many instances, the terms "about" may include
numbers that are rounded to the nearest significant figure.
[0015] Weight percent, percent by weight, wt%, wt-%, % by weight, and the like are synonyms
that refer to the concentration of a substance as the weight of that substance divided
by the weight of the composition and multiplied by 100.
[0016] The recitation of numerical ranges by endpoints includes all numbers within that
range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).
[0017] As used in this specification and the appended claims, the singular forms "a", "an",
and "the" include plural referents unless the content clearly dictates otherwise.
As used in this specification and the appended claims, the term "or" is generally
employed in its sense including "and/or" unless the content clearly dictates otherwise.
[0018] The following description should be read with reference to the drawings wherein like
reference numerals indicate like elements throughout the several views. The drawings,
which are not necessarily to scale, depict illustrative embodiments of the claimed
invention. For example, although discussed with specific reference to guidewires in
the particular embodiments described herein, the invention may be applicable to a
variety of medical devices that are adapted to be advanced into the anatomy of a patient
through an opening or lumen. For example, the invention may be applicable to fixed
wire devices, catheters (e.g., guide, balloon, stent delivery, etc.), drive shafts
for rotational devices such as atherectomy catheters and IVUS catheters, endoscopic
devices, laproscopic devices, embolic protection devices, spinal or cranial navigational
devices, and other such devices. Additionally, while some embodiments may be adapted
or configured for use within the vasculature of a patient, other embodiments may be
adapted and/or configured for use in other anatomies. It is to be understood that
a broad variety of materials, dimensions and structures can be used to construct suitable
embodiments, depending on the desired characteristics. The following examples of some
embodiments are included by way of example only, and are not intended to be limiting.
[0019] Refer now to Figure 1, which is a perspective view of a coil 110, incorporated into
an elongate medical device 100. The elongate medical device 100 may include an elongate
shaft or core 130. The elongate shaft or core 130 can have a proximal end 131 and
an opposing distal end 132. The coil 110 can be disposed on a portion of the elongate
shaft, for example, at the distal end 132. A distal tip 140 can be disposed on an
end of the coil 110 and/or the elongate shaft or core 130. The coil 110 may have a
plurality of windings 105 that form a coil length L.
[0020] The coil 110 can be formed of a variety of materials including metals, metal alloys,
polymers, and the like. Some examples of material for use in the coil 110 include
a metal or a metal alloy such as a stainless steel, such as 304V, 304L, and 316L stainless
steel; alloys including nickel-titanium alloy such as linear elastic or superelastic
(i.e., pseudoelastic) nitinol; nickel-chromium alloy; nickel-chromium-iron alloy;
cobalt alloy; tungsten or tungsten alloys; MP35-N (having a composition of about 35%
Ni, 35% Co, 20% Cr, 9.75% Mo, a maximum 1% Fe, a maximum 1% Ti, a maximum 0.25% C,
a maximum 0.15% Mn, and a maximum 0.15% Si); hastelloy; monel 400; inconel 625; or
the like; or other suitable material, or combinations or alloys thereof.
[0021] Further examples of suitable alloys include silver-cadmium alloy, gold-cadmium alloy,
gold-copper-zinc alloy, copper-aluminum-nickel alloy, copper-gold-zinc alloy, copper-zinc
alloy, copper-zinc-aluminum alloy, copper-zinc-tin alloy, copper-zinc-silicon alloy,
iron-beryllium alloy, iron-platinum alloy, indium-thallium alloy, iron-manganese alloy,
nickel-titanium-cobalt alloy, and copper-tin alloy.
[0022] Some additional examples of suitable material include a polymer material, such as,
for example, a high performance polymer. The material forming the coil 110 wire may
be a material with a high Poisson's ratio, such as, a value greater than 0.25 or 0.3
or 0.4 or 0.5. A material forming the wire for the coil 110 with a high Poisson's
ratio can provide a coil with a higher torque-ability to flexibility ratio.
[0023] In some embodiments, the coil 110 or portions thereof can be made of, or coated or
plated with, or otherwise include a radiopaque material. Radiopaque materials are
understood to be materials capable of producing a relatively bright image on a fluoroscopy
screen or another imaging technique during a medical procedure. This relatively bright
image aids the user of medical device 100 in determining its location. Some examples
of radiopaque materials can include, but are not limited to, gold, platinum, palladium,
tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the
like, or combinations or alloys thereof.
[0024] Additionally, the coil 110, or other portions of the device 100, can include materials
or structure to impart a degree of MRI compatibility. For example, to enhance compatibility
with Magnetic Resonance Imaging (MRI) machines, it may be desirable to make the coil
110, or other portions of the medical device 100, in a manner that would impart a
degree of MRI compatibility. For example, the elongate shaft or core 130, the coil
110, or portions thereof, or other portions of the device 100, may be made of a material
that does not substantially distort the image and create substantial artifacts (artifacts
are gaps in the image). Certain ferromagnetic materials, for example, may not be suitable
because they may create artifacts in an MRI image. The elongate shaft or core 130,
the coil 110, or portions thereof, may also be made from a material that the MRI machine
can image. Some materials that exhibit these characteristics include, for example,
tungsten, Elgiloy, MP35N, nitinol, and the like, and others, or combinations or alloys
thereof. The wire that forms the coil 110 may be formed of a homogenous material or
be a composite structure.
[0025] In some embodiments, the coil 110 can be made of a material that is compatible with
the core wire 130 and the distal tip 140. The particular material used can be chosen
in part based on the desired flexibility requirements or other desired characteristics.
In some particular embodiments, the coil 110 can be formed from a superelastic or
linear elastic nickel-titanium alloy, for example, linear elastic or superelastic
nitinol.
[0026] The word nitinol was coined by a group of researchers at the United States Naval
Ordinance Laboratory (NOL) who were the first to observe the shape memory behavior
of this material. The word nitinol is an acronym including the chemical symbol for
nickel (Ni), the chemical symbol for titanium (Ti), and an acronym identifying the
Naval Ordinance Laboratory (NOL). Within the family of commercially available nitinol
alloys, is a category designated "super elastic" (i.e., pseudoelastic) and a category
designated "linear elastic". Although these two categories of material are similar
in chemistry, they each exhibit distinct and useful mechanical properties. Either,
or both superelastic and linear elastic nitinol can be used.
[0027] One example of a suitable nickel-titanium alloy that may exhibit linear elastic properties
is FHP-NT alloy commercially available from Furukawa Techno Material Co. of Kanagawa,
Japan. Some examples of suitable nickel-titanium alloys that may exhibit linear elastic
characteristics include those disclosed in
U.S. Patent Nos. 5,238,004 and
6,508,803.
[0028] The coil 110 can be formed of a wire having shapes disclosed below and ranging in
dimensions to achieve the desired flexibility. It can also be appreciated that other
cross-sectional shapes or combinations of shapes may be utilized without departing
from the spirit of the invention. For example, the cross-sectional shape of wire used
to make the coil may be a circle, oval, rectangular, square, I-Beam, triangle, polygonal,
and the like, or any suitable shape as further described below.
[0029] In some embodiments, the coil 110 can be wrapped in a helical fashion by conventional
winding techniques. The pitch of adjacent turns of the coil 110 may be tightly wrapped
so that each turn, at least in part, touches or is in close proximity to the succeeding
turn, the pitch may be set such that the coil 110 is wrapped in an open fashion, or
co-wound with a second coil as further described below. The coil 110 has a longitudinal
axis x, and a radial axis y orthogonal to the longitudinal axis x as indicated by
coordinate axis in Figures 1-8. The longitudinal axis x is parallel to the length
L of the coil 110.
[0030] Such a coil 110, as discussed herein, can be incorporated into a broad variety of
medical devices. For example, as shown in Figure 1, the coil 110 can be incorporated
into an elongate medical device 100, such as a guidewire, that may include an elongate
shaft or core 130. The coil 110 can be disposed on a portion of the elongate shaft,
for example, proximate the distal end 132. It should be understood, however, that
such a coil can be incorporated into a broad variety of medical devices.
[0031] With reference to the embodiment shown in Figure 1, the elongate shaft or core 130
can have a solid cross-section or a hollow cross-section. In other embodiments, the
elongate shaft or core 130 can include a combination of areas having solid cross-sections
and hollow cross sections. Moreover, the elongate shaft or core 130 can be made of
rounded wire, flattened ribbon, or other such structures having various cross-sectional
geometries. The cross-sectional geometries along the length of the elongate shaft
or core 130 can also be constant or can vary. For example, Figure 1 depicts the elongate
shaft or core 130 as having a generally round cross-sectional shape. It can be appreciated
that other cross-sectional shapes or combinations of shapes may be utilized without
departing' from the spirit of the invention. For example, the cross-sectional shape
of the elongate shaft or core 130 may be oval, rectangular, square, polygonal, and
the like, or any suitable shape.
[0032] In some embodiments, the elongate shaft or core 130 can be formed of any suitable
metallic, polymeric or composite material. In some embodiments, part or all of the
elongate shaft or core 130 can be formed of a metal or a metal alloy such as a stainless
steel, such as 304V, 304L, and 316L stainless steel; alloys including nickel-titanium
alloy such as linear elastic or superelastic (i.e., pseudoelastic) nitinol; nickel-chromium
alloy; nickel-chromium-iron alloy; cobalt alloy; tungsten or tungsten alloys; MP35-N
(having a composition of about 35% Ni, 35% Co, 20% Cr, 9.75% Mo, a maximum 1 % Fe,
a maximum 1 % Ti, a maximum 0.25% C, a maximum 0.15% Mn, and a maximum 0.15% Si);
hastelloy; monel 400; inconel 625; or the like; or other suitable material, or combinations
or alloys thereof.
[0033] Further examples of suitable alloys include silver-cadmium alloy, gold-cadmium alloy,
gold-copper-zinc alloy, copper-aluminum-nickel alloy, copper-gold-zinc alloy, copper-zinc
alloy, copper-zinc-aluminum alloy, copper-zinc-tin alloy, copper-zinc-silicon alloy,
iron-beryllium alloy, iron-platinum alloy, indium-thallium alloy, iron-manganese alloy,
nickel-titanium-cobalt alloy, and copper-tin alloy.
[0034] The particular material used can be chosen in part based on the desired flexibility
requirements or other desired characteristics or the elongate shaft or core 130. In
some particular embodiments, the elongate shaft or core 130 can be formed from a superelastic
or linear elastic nickel-titanium alloy, for example, those discussed above with regard
to the coil 110.
[0035] The entire elongate shaft or core 130 can be made of the same material, or in some
embodiments, can include portions or sections that are made of different materials.
In some embodiments, the material used to construct different portions of the core
wire 130 can be chosen to impart varying flexibility and stiffness characteristics
to different portions of the wire. For example, a proximal portion 131 and a distal
portion 132 can be formed of different materials (i.e., materials having different
moduli of elasticity) resulting in a difference in flexibility. In some embodiments,
the material used to construct the proximal portion 131 can be relatively stiff for
push-ability and torque-ability, and the material used to construct the distal portion
132 can be relatively flexible by comparison for better lateral track-ability and
steer-ability. To illustrate, the proximal portion 131 can be formed of, for example,
straightened 304v stainless steel wire, and the distal portion 130 can be formed of,
for example, a straightened super elastic or linear elastic alloy (e.g., nickel-titanium)
wire.
[0036] In embodiments where different portions of elongate shaft or core 130 are made of
different material, the different portions can be connected using any suitable connecting
techniques. For example, the different portions of the elongate shaft or core 130
can be connected using welding, soldering, brazing, adhesive, or the like, or combinations
thereof. Additionally, some embodiments can include one or more mechanical connectors
or connector assemblies to connect the different portions of the elongate shaft or
core 130 that are made of different materials. The connector may include any structure
generally suitable for connecting portions of a elongate shaft or core 130. One example
of a suitable structure includes a structure such as a hypotube or a coiled wire which
has an inside diameter sized appropriately to receive and connect the different portions
of the elongate shaft or core 130. Some methods and structures that can be used to
interconnect different shaft sections are disclosed in
U.S. Patent Application Nos. 09/972,276, and
10/086,992.
[0037] In some embodiments, portions or all of the elongate shaft or core 130, the coil
110, or other structures included within the medical device 100 may also be doped
with, coated or plated with, made of, or otherwise include a radiopaque material.
Additionally, in some embodiments, a degree of MRI compatibility can be imparted into
the medical device 100, as discussed above.
[0038] The elongate shaft or core 130 may include one or more tapers or tapered regions.
The tapered regions may be linearly tapered, tapered in a curvilinear fashion, uniformly
tapered, non-uniformly tapered, or tapered in a step-wise fashion. The angle of any
such tapers can vary, depending upon the desired flexibility and torque transmission
characteristics. The length of the taper may be selected to obtain a more (longer
length) or less (shorter length) gradual transition in stiffness. It can be appreciated
that essentially any portion of the elongate shaft or core 130 may be tapered and
the taper can be in either the proximal or the distal direction. The number, arrangement,
size, and length of the tapering and constant diameter portions can be varied to achieve
the desired characteristics, such as flexibility and torque transmission characteristics.
[0039] The distal tip 140 can be formed from a variety of different materials, depending
on desired performance characteristics. In some embodiments, the distal tip can form
an atraumatic portion on the distal end of the device 100. In some embodiments, the
distal tip 140 can be formed of a material such as a metallic material that is amenable
to being welded, soldered, or otherwise attached to the distal end 132 of the elongate
shaft or core 130. For example, in some embodiments, the distal tip 140 can be a solder
tip that is disposed via soldering at the distal end of the device and forms an atraumatic
rounded portion. In other embodiments, the distal tip can be a prefabricated, or partially
prefabricated, structure that is thereafter attached to the distal end of the device
using suitable attachment techniques, such as welding, soldering, brazing, crimping,
friction fitting, adhesive bonding, mechanical interlocking and the like. A variety
of different processes, such as soldering, deep drawing, roll forming or metal stamping,
metal injection molding, casting and the like, can be used to form the distal tip
140.
[0040] In some embodiments, it may be beneficial, but not always necessary, that the distal
tip 140 to be formed of a material that is compatible with the particular joining
technique used to connect the tip 140 to the other structure. For example, in some
particular embodiments, it can be beneficial but not necessary for the distal tip
140 to be formed of the same metal or metal alloy as the distal end 132 of the elongate
shaft or core 130. For example, if the elongate shaft or core 130 is formed of stainless
steel, it can be beneficial for the distal tip 140 to be formed of stainless steel.
In other embodiments, both of the distal tip 140 and the distal end 132 of the elongate
shaft or core 130 can be formed of the same metal alloy, such as nitinol.
[0041] To form the assembly 100 shown in Figure 1, the coil 110 can be disposed over the
elongate shaft or core 130 as illustrated. The coil 110 can be secured to the elongate
shaft or core 130 in any suitable manner, including for example welding, soldering,
brazing, crimping, friction fitting, adhesive bonding, mechanical interlocking and
the like. In the embodiment shown, the coil 110 can be secured at its proximal end
to the elongate shaft or core 130 at a proximal attachment point 133, and can be secured
at its distal end to the elongate shaft or core 130 via the distal tip 140. In some
embodiments, the distal tip 140 is a solder tip or a weld tip that is soldered or
welded to the elongate shaft or core 130 and the coil 110, and forms an atraumatic
tip. In other embodiments, the distal tip 140 is prefabricated, or partially prefabricated,
and is connected to the elongate shaft or core 130 and the coil 110 using a suitable
attachment technique.
[0042] In some embodiments, the coil 110 and/or the distal tip can be welded to the elongate
shaft or core 130. It is to be appreciated that various welding processes can be utilized
without deviating from the spirit and scope of the invention. In general, welding
refers to a process in which two materials such as metal or metal alloys are joined
together by heating the two materials sufficiently to at least partially melt adjoining
surfaces of each material. A variety of heat sources can be used to melt the adjoining
materials. Examples of welding processes that can be suitable in some embodiments
include LASER welding, resistance welding, TIG welding, microplasma welding, electron
beam, and friction or inertia welding.
[0043] LASER welding equipment that may be suitable in some embodiments is commercially
available from Unitek Miyachi of Monrovia, California and Rofin-Sinar Incorporated
of Plymouth, Michigan. Resistance welding equipment that may be useful in some embodiments
is commercially available from Palomar Products Incorporated of Carlsbad, California
and Polaris Electronics of Olathe, Kansas. TIG welding equipment that may be useful
in some embodiments is commercially available from Weldlogic Incorporated of Newbury
Park, California. Microplasma welding equipment that may be useful in some embodiments
is commercially available from Process Welding Systems Incorporated of Smyrna, Tennessee.
[0044] In some embodiments, laser or plasma welding can be used to secure the distal tip
140, the coil 110 and the elongate shaft or core 130 securely together. In laser welding,
a light beam is used to supply the necessary heat. Laser welding can be beneficial
in the processes contemplated by the invention, as the use of a laser light heat source
can provide pinpoint accuracy. In some embodiments, laser diode soldering can be useful.
[0045] It should also be understood that the device 100 can include additional structure,
such as shaping ribbons, marker bands and/or coils, additional inner or outer coils,
inner or outer sheaths, and the like. Those of skill in the art and others will recognize
how to incorporate such additional structures into the device, as is generally known.
[0046] Figure 2 is a partial side elevation view of another example embodiment of a coil
200 having a coil length L. The coil 200 has a longitudinal axis x, and a radial axis
y orthogonal to the longitudinal axis x.
[0047] Figure 3 is a cross-sectional view of an example coil 300. The coil 300 has a longitudinal
axis x, and a radial axis y orthogonal to the longitudinal axis x and a lumen 307.
The coil 300 is formed from a wire 305 having a cross-section. The coil 300 coordinate
system can be transposed directly onto the wire 305 cross-section as described below.
The wire 305 cross-section is shown as rectangular; however, the wire 305 cross-section
may be any shape conforming to the limits described herein.
[0048] Figure 4 is a cross-sectional view of an example wire 400 forming a coil. The wire
400 has a cross-sectional area 401 defined by an inner surface 410, an opposing outer
surface 420 and parallel walls 415 connecting the inner surface 410 and the outer
surface 420. The inner surface 410 defines a lumen (307) of the coil and the outer
surface 420 defines an outer surface of the coil (300). The cross-sectional area 401
shown corresponds to a rectangle having longer radial walls 415 than longitudinal
walls 410, 420.
[0049] The cross-sectional area 401 has a centroid 450 a longitudinal axis x parallel to
the coil longitudinal axis, and a radial axis y parallel to the coil radial axis and
orthogonal to the longitudinal axis x. The centroid 450 may be a point which defines
the geometric center of a cross-sectional surface area or object. The longitudinal
axis x intersects the radial axis y at the centroid 450. The centroid 450 of any cross-sectional
area or object is easily determined through basic geometric mathematics. The cross-sectional
area 401 has a moment of inertia I
x with respect to an axis running through the centroid 450 and parallel to the longitudinal
axis x of the coil. This is also referred to as I
x or the moment of inertia of a plane area with respect to the x axis. The cross-sectional
area 401 has a moment of inertia I
y with respect to an axis running through the centroid 450 and parallel to the radial
axis y of the coil. This is also referred to as I
y or the moment of inertia of a plane area with respect to the y axis. These are defined
by the integrals:
in which x and y are the coordinates of the differential elements of area dA. The
moment of inertia I
x with respect to an axis running through the centroid 450 and parallel to the longitudinal
axis x of the coil is greater than the moment of inertia I
y with respect to an axis running through the centroid 450 and parallel to the radial
axis y of the coil.
[0050] Figure 5 is a cross-sectional view of an example wire 500 forming a coil. The wire
500 has a cross-sectional area 501 defined by an inner surface 510, an opposing outer
surface 520 and curved walls 515 connecting the inner surface 510 and the outer surface
520. The inner surface 510 defines a lumen (307) of the coil and the outer surface
520 defines an outer surface of the coil (300). The cross-sectional area 501 shown
corresponds to an ellipse having longer radial walls 515 than longitudinal walls 510,
520.
[0051] The cross-sectional area 501 has a centroid 550 as defined above, a longitudinal
axis x parallel to the coil longitudinal axis, and a radial axis y parallel to the
coil radial axis and orthogonal to the longitudinal axis x. The cross-sectional area
501 has a moment of inertia I
x (as defined above) with respect to an axis running through the centroid 550 and parallel
to the longitudinal axis x of the coil. The cross-sectional area 501 has a moment
of inertia I
y (as defined above) with respect to an axis running through the centroid 550 and parallel
to the radial axis y of the coil. The moment of inertia I
x with respect to an axis running through the centroid 550 and parallel to the longitudinal
axis x of the coil is greater than the moment of inertia Iy with respect to an axis
running through the centroid 550 and parallel to the radial axis y of the coil.
[0052] Figure 6 is a cross-sectional view of an example wire 600 forming a coil. The wire
600 has a cross-sectional area 601 defined by an inner surface 610, an opposing outer
surface 620 and walls 615 connecting the inner surface 610 and the outer surface 620.
The inner surface 610 defines a lumen (307) of the coil and the outer surface 620
defines an outer surface of the coil (300). The cross-sectional area 601 shown corresponds
to an I-Beam shape.
[0053] The cross-sectional area 601 has a centroid 650 as defined above, a longitudinal
axis x parallel to the coil longitudinal axis, and a radial axis y parallel to the
coil radial axis and orthogonal to the longitudinal axis x. The cross-sectional area
601 has a moment of inertia I
x (as defined above) with respect to an axis running through the centroid 650 and parallel
to the longitudinal axis x of the coil. The cross-sectional area 601 has a moment
of inertia Iy (as defined above) with respect to an axis running through the centroid
650 and parallel to the radial axis y of the coil. The moment of inertia I
x with respect to an axis running through the centroid 650 and parallel to the longitudinal
axis x of the coil is greater than the moment of inertia I
y with respect to an axis running through the centroid 650 and parallel to the radial
axis y of the coil.
[0054] The described wire shapes can be manufactured in a variety of ways such as, for example,
extrusion, winding, 3D photo-etching, laser cutting, drawing, or the like. As will
be apparent to those skilled in the art, the above-listed cross-sectional shapes are
merely illustrative and various other shapes meeting the criteria set out herein may
also be used in the practice of the invention.
[0055] Figure 7 is a cross-sectional view of an example composite wire 700 forming a coil.
Figure 7 is similar in shape to Figure 4; however, Figure 7 is an example of a composite
wire 700 used to form the coil. While a rectangular shape is shown, any shape may
be used such as circular or square including the shapes disclosed above to form the
composite wire. A composite wire 700 can provide the features of the invention when
the actual geometry of the wire is constrained to a circle or square shape.
[0056] The composite wire 700 has a centroid 750, a wire longitudinal axis x parallel to
the coil longitudinal axis x and a wire radial axis y parallel to the coil radial
axis y. A first material 710 having a first Young's Modulus is disposed at the centroid
750 and a second material 720 having a second Young's Modulus is disposed further
away from the centroid 750 than the first material 710 along the wire radial axis
y. The second material's 720 Young's Modulus is greater than the first material's
710 Young's Modulus. Thus, the second material 720 is stiffer than the first material.
The second material 720 Young's Modulus may be 1% to 1000% or 10% to 500% or 20% to
300% or 20% to 200% or 20% to 100% greater than the first material 710 Young's Modulus.
The second material 720 Young's Modulus may be 1%, 10%, 20%, 50%, 100%, 200%, 300%,
500%, 1000%, or 2000% greater than the first material 710 Young's Modulus. The composite
wire 700 may be formed by co-extrusion for plastic composite wire 700 or by ion deposition
or fusing for metallic composite wire 700.
[0057] An example of a metallic composite wire 700 may be where the first material 710 is
nitinol (10 Mpsi) and the second material 710 is stainless steel (30 Mpsi). Another
example of a plastic composite wire 700 may be where the first material 710 is a polyurethane
(2 ksi) and the second material 710 is a poly-ether-ether-ketone (500 ksi).
[0058] The described wire shapes can be manufactured in a variety of ways such as, for example,
co-extrusion, winding, 3D photo-etching, laser cutting, or the like. As will be apparent
to those skilled in the art, the above-listed materials are merely illustrative and
various other materials meeting the criteria set out above may also be used in the
practice of the invention.
[0059] A coil-wire cross-section that moves material away from the x-axis without moving
the same amount of material away from the centroid and y-axis will increase the torque-ability/flexibility
ration of the coil. Increasing the moment of inertia about the x-axis of the cross-section
of the coil-wire increases the torsional rigidity of the coil. Not increasing the
polar moment of inertia about the centroid of the cross-section of the coil-wire as
fast makes the coil more flexible. Thus, increasing the moment of inertia about the
x-axis and not increasing the polar moment of inertia about the centroid as rapidly
will provide a coil that efficiently transmits torque without sacrificing the flexibility
of the coil. The moment of inertia about the x-axis can be 1% to 1000%, 10% to 500%,
20% to 300%, 20% to 200%, 50% to 100% greater than the moment of inertia about the
y-axis. The moment of inertia about the x-axis can be 1%, 5%, 10%, 20%, 30%, 40%,
50%, 75%, 100%, 200%, 300%, 500%, 1000%, or 2000% greater than the moment of inertia
about the y-axis.
[0060] Figure 8 is a cross-sectional view of an example co-wound coil 800. First coil elements
810 can be co-wound with second coil elements 820 to produce a co-wound coil 800.
First coil elements 810 can have a moment of inertia I
x with respect to an axis running through the centroid 850 and parallel to the longitudinal
axis x of the coil being greater than a moment of inertia Iy with respect to an axis
running through the centroid 850 and parallel to the radial axis y of the coil. The
second coil elements 820 can be any shape such as a circle or square and be made of
any suitable material. The second coil elements 820 space the first coil elements
810 away from each other. This co-wound coil 800 enhances the properties of the device
while reducing pinching of the target vessel wall by the coil 800.
[0061] Figure 9 is a cross-sectional view of the guidewire 900 with a coil 910 in accordance
with the invention. The guidewire 900 includes a core 930. The core may have a proximal
section 931 and an opposing distal section 932. The distal section 932 can include
a series of tapered and constant diameter sections as illustrated in Figure 9. In
other embodiments, the proximal section 931 may also include a series of tapered and
constant diameter sections. The tapered regions may be linearly tapered, tapered in
a curvilinear fashion, uniformly tapered, non-uniformly tapered, or tapered in a step-wise
fashion. The angle of any such tapers can vary, depending upon the desired flexibility
characteristics. The length of the taper may be selected to obtain a more (longer
length) or less (shorter length) gradual transition in stiffness. It can be appreciated
that essentially any portion of guidewire 900 and/or guidewire sections 931/932 may
be tapered and the taper can be in either the proximal or the distal direction. In
some other embodiments, a guidewire core wire can have a profile in which the core
wire has a greater number of constant diameter sections, separated by a greater number
of taper sections. In some embodiments, a guidewire core wire can have fewer or no
tapers. The tapers can be as illustrated in Figure 9, or they can be longer (more
gradual), or shorter (less gradual).
[0062] The tapered and constant diameter portions of the tapered region may be formed by
any one of a number of different techniques, for example, by centerless grinding methods,
stamping methods, and the like. The centerless grinding technique may utilize an indexing
system employing sensors (e.g., optical/reflective, magnetic) to avoid excessive grinding
of the connection. In addition, the centerless grinding technique may utilize a CBN
or diamond abrasive grinding wheel that is well shaped and dressed to avoid grabbing
core wire during the grinding process. Some examples of suitable grinding methods
are disclosed in
U.S. Patent Application No. 10/346,698. The narrowing and constant diameter portions as shown in Figure 9 are not intended
to be limiting, and alterations of this arrangement can be made without departing
from the invention. One of skill will recognize that a guidewire core wire can have
a profile different from that illustrated in Figure 9.
[0063] The coil 910 can be disposed about a portion of the core distal section 932. The
core 930 can be formed from a variety of materials as described above and provide
the features described above. The coil 910 can be disposed between the core 930 and
a distal tip 940 and constructed as described above.
[0064] A guidewire in accordance with some embodiments of the invention can optionally include
a coating layer 960 such as a lubricious coating layer over part or all of the guidewire
assembly 900. Hydrophobic coatings such as fluoropolymers provide a dry lubricity
which improves guide wire handling and device exchanges. Lubricious coatings improve
steer-ability and improve lesion crossing capability. Suitable lubricious polymers
are well known in the art and may include hydrophilic polymers such as polyarylene
oxides, polyvinylpyrolidones, polyvinylalcohols, hydroxy alkyl cellulosics, algins,
saccharides, caprolactones, and the like, and mixtures and combinations thereof. Hydrophilic
polymers may be blended among themselves or with formulated amounts of water insoluble
compounds (including some polymers) to yield coatings with suitable lubricity, bonding,
and solubility. In some embodiments, the more distal portion 932 of the guidewire
is coated with a hydrophilic polymer and the more proximal portion 931 is coated with
a fluoropolymer 960, such as polytetrafluoroethylene (PTFE).
[0065] Figure 10 is a cross-sectional view of the alternative guidewire 1000 with a coil
1010 in accordance with the invention. The coil 1010 is disposed over a portion of
the core 1030 and a polymer sheath or sleeve 1070 is disposed over the core 1030 and
coil 1010. The coil 1010 is described above.
[0066] In this embodiment a polymer tip guidewire 1000 is formed by including the polymer
sheath or sleeve 1070 that forms a rounded tip over the coil 1010. The polymer sheath
or sleeve 1070 can be made from any material that can provide the desired strength,
flexibility or other desired characteristics. The polymer sheath or sleeve 1070 can
in some non-limiting embodiments have a length that is in the range of about 2 centimeters
to about 300 centimeters and can have an inner diameter that is in the range of about
51 µm (0.002 inches) to about 762 µm (0.030 inches) and an outer diameter that is
in the range of about 305µm (0.012 inches) to about 965µm (0.038 inches).
[0067] The use of a polymer can serve several functions, such as improving the flexibility
properties of the guidewire assembly. Choice of polymers for the sheath or sleeve
1070 will vary the flexibility of the guidewire. For example, polymers with a low
durometer or hardness will make a very flexible or floppy tip. Conversely, polymers
with a high durometer will make a tip that is stiffer. The use of polymers for the
sleeve can also provide a more atraumatic tip for the guidewire. An atraumatic tip
is better suited for passing through body passages. Finally, a polymer can act as
a binder for radiopaque materials, as discussed in more detail below.
[0068] Some suitable materials include polymers, and like material. Examples of suitable
polymer material include any of a broad variety of polymers generally known for use
as guidewire polymer sleeves. In some embodiments, the polymer material used is a
thermoplastic polymer material. Some examples of some suitable materials include polyurethane,
elastomeric polyamides, block polyamide/ethers (such as Pebax), silicones, and co-polymers.
The sleeve may be a single polymer, multiple layers, or a blend of polymers. By employing
careful selection of materials and processing techniques, thermoplastic, solvent soluble
and thermosetting variants of these materials can be employed to achieve the desired
results.
[0069] Further examples of suitable polymeric materials include but are not limited to poly(L-lactide)
(PLLA), poly(D,L-lactide) (PLA), polyglycolide (PGA), poly(L-lactide-co-D,L-lactide)
(PLLA/PLA), poly(L-lactide-co-glycolide) (PLLA/PGA), poly(D, L-lactide-co-glycolide)
(PLA/PGA), poly(glycolide-co-trimethylene carbonate) (PGA/PTMC), polyethylene oxide
(PEO), polydioxanone (PDS), polycaprolactone (PCL), polyhydroxylbutyrate (PHBT), poly(phosphazene),
poly D,L-lactide-co-caprolactone) (PLA/PCL), poly(glycolide-co-caprolactone) (PGA/PCL),
polyanhydrides (PAN), poly(ortho esters), poly(phosphate ester), poly(amino acid),
poly(hydroxy butyrate), polyacrylate, polocacrylamid, poly(hydroxyethyl methacrylate),
polyurethane, polysiloxane and their copolymers.
[0070] In some embodiments, the sheath or sleeve 1070, or portions thereof, can include,
or be doped with, radiopaque material to make the sheath or sleeve 1070, or portions
thereof, more visible when using certain imaging techniques, for example, fluoroscopy
techniques. Any suitable radiopaque material known in the art can be used. Some examples
include precious metals, tungsten, barium subcarbonate powder, and the like, and mixtures
thereof. In some embodiments, the polymer can include different sections having different
amounts of loading with radiopaque material. For example, the sheath or sleeve 1070
can include a distal section having a higher level of radiopaque material loading,
and a proximal section having a correspondingly lower level of loading.
[0071] In some embodiments, it is also contemplated that a separate radiopaque member or
a series of radiopaque members, such as radiopaque coils, bands, tubes, or other such
structures could be attached to the guidewire core wire 1030, or incorporated into
the core wire by plating, drawing, forging, or ion implantation techniques.
[0072] The sheath or sleeve 1070 can be disposed around and attached to the guidewire assembly
1000 using any suitable technique for the particular material used. In some embodiments,
the sheath or sleeve 1070 can be attached by heating a sleeve of polymer material
to a temperature until it is reformed around the guidewire assembly 1000. In some
other embodiments, the sheath or sleeve 1070 can be attached using heat shrinking
techniques. In other embodiments, the sheath or sleeve 1070 can be co-extruded with
the core wire 1030. The sleeve 1070 can be finished, for example, by a centerless
grinding or other method, to provide the desired diameter and to provide a smooth
outer surface.
[0073] Figure 11 is a cross-sectional view of the alternative guidewire 1100 with a coil
1110 in accordance with the invention. The coil 1110 is described above. The guidewire
1100 includes a core 1130. The core may have a proximal section 1131 and an opposing
distal section 1132. The distal section 1132 can include a series of taper and constant
diameter sections as illustrated in Figure 11. The coil 1110 can be disposed about
a portion of the core distal section 1132. The core 1130 can be formed from a variety
of materials as described above. The coil can be disposed between the core 1130 and
a distal tip 1140 and constructed as described above. A wire or ribbon 1180 can be
disposed between the distal tip 1140 and core 1130.
[0074] The wire or ribbon 1180 can be attached adjacent the distal end 1132 of the core
1130, and extend distally to the distal tip 1140. In some embodiments, the wire or
ribbon 1180 can be a fabricated or formed wire structure, for example a coiled wire.
In the embodiment shown, the ribbon 1180 is a generally straight wire that overlaps
with and is attached to the constant diameter region 1133 at attachment point 1134.
In some embodiments, the ribbon 1180 overlaps with the constant diameter section 1133
by a length in the range of about 1.27 to 25.4 mm (about 0.05 to 1.0 inch), but in
other embodiments, the length of the overlap can be greater or less.
[0075] The ribbon 1180 can be made of any suitable material and sized appropriately to give
the desired characteristics, such as strength and flexibility characteristics. Some
examples of suitable materials include metals, metal alloys, polymers, and the like.
In some embodiments, the ribbon 1180 may be formed of a metal or metal alloy such
as stainless steel, nickel-chromium alloy, nickel-chromium-iron alloy, cobalt alloy,
a nickel-titanium alloy, such as a straightened super elastic or linear elastic alloy
(e.g., nickel-titanium) wire. The ribbon 1180 can be attached using any suitable attachment
technique. Some examples of attachment techniques include soldering, brazing, welding,
adhesive bonding, crimping, or the like. In some embodiments, the ribbon or wire 1180
can function as a shaping structure or a safety structure.
[0076] A guidewire 1100 in accordance with some embodiments of the invention can optionally
include a coating layer 1160 such as a lubricious coating layer over part or all of
the guidewire assembly 1100 or even over part. Hydrophobic coatings such as fluoropolymers
provide a dry lubricity which improves guide wire handling and device exchanges. Lubricious
coatings improve steer-ability and improve lesion crossing capability. Suitable lubricious
polymers are well known in the art and may include hydrophilic polymers such as polyarylene
oxides, polyvinylpyrolidones, polyvinylalcohols, hydroxy alkyl cellulosics, algins,
saccharides, caprolactones, and the like, and mixtures and combinations thereof. Hydrophilic
polymers may be blended among themselves or with formulated amounts of water insoluble
compounds (including some polymers) to yield coatings with suitable lubricity, bonding,
and solubility. In some embodiments, the more distal portion 1132 of the guidewire
is coated with a hydrophilic polymer and the more proximal portion 1131 is coated
1160 with a fluoropolymer, such as polytetrafluroethylene (PTFE).
[0077] In some other embodiments, a guidewire core wire can have a profile in which the
core wire has a greater number of constant diameter sections, separated by a greater
number of taper sections. In some embodiments, a guidewire core wire can have fewer
or no tapers. The tapers can be as illustrated in Figure 11, or they can be longer
(more gradual), or shorter (less gradual).
[0078] One of skill will recognize that a guidewire core wire can have a profile different
from that illustrated in Figures 9, 10 and 11. For example, the core wire 930, 1030,
1130 can be continuously tapered, can have a tapered section or a number or series
of tapered sections of differing diameters, or can have a constant diameter. In some
embodiments, core wire 930, 1030, 1130 is tapered or otherwise formed to have a geometry
that decreases in cross sectional area toward the distal end thereof. If tapered,
core wire 930, 1030, 1130 can include a uniform or a non-uniform transition of the
sections, depending on the transition characteristics desired. For example, core wire
930, 1030, 1130 may be linearly tapered, tapered in a curvilinear fashion, or tapered
in a step-wise fashion. The angle of any such tapers can vary, depending upon the
desired flexibility characteristics. The length of the taper may be selected to obtain
a more (longer length) or less (shorter length) gradual transition in stiffness.
[0079] Similar to what is described above, the structure used to construct the core wire
930, 1030, 1130 can be designed such that a proximal portion 931, 1031, 1131 is relatively
stiff for push-ability and torque-ability, and distal portion 932, 1032, 1132 is relatively
flexible by comparison for better lateral track-ability and steer-ability. For example,
in some embodiments, a proximal portion 931, 1031, 1131 has a constant or generally
uniform diameter along its length to enhance stiffness. However, embodiments including
a proximal portion 931, 1031, 1131 having a tapered portion or a series of tapered
portions are also contemplated. The diameter of the proximal portion 931, 1031, 1131
can be sized appropriately for the desired stiffness characteristics dependent upon
the material used. For example, in some embodiments, a proximal portion 931, 1031,
1131 can have a diameter in the range of about 254µm to about 635µm (about 0.010 to
about 0.025 inches) or greater, and in some embodiments, in the range of about 254µm
to about 457µm (about 0.010 to about 0.018 inches) or greater.
[0080] A distal portion 932, 1032, 1132 can likewise be constant diameter, can be continuously
tapered, or can have a tapered section or a number or a series of tapered sections
of differing diameters. In embodiments where the structure of core wire 930, 1030,
1130 is designed such that a distal portion 932, 1032, 1132 is relatively flexible
by comparison to the proximal portion 931, 1031, 1131, the distal portion 932, 1032,
1132 can include at least one tapered or reduced diameter portion for better flexibility
characteristics.
[0081] The lengths of the proximal portions 931, 1031, 1131 and distal portions 932, 1032,
1132 are typically, but not always dictated by the length and flexibility characteristics
desired in the final medical device. In some embodiments, the proximal portion 931,
1031, 1131 can have a length in the range of about 50 to about 300 centimeters, and
the distal portion 932, 1032, 1132 can have a length in the range of about 3 to about
50 centimeters.
[0082] The core wire 930, 1030, 1130 can have a solid cross-section as shown, but in some
embodiments, can have a hollow cross-section. In yet other embodiments, core wire
930, 1030, 1130 can include a combination of areas having solid cross-sections and
hollow cross sections.
[0083] The tapered and constant diameter portions can be formed by any one of a number of
different techniques, for example, by centerless grinding, stamping and the like.
A centerless grinding technique can utilize an indexing system employing sensors (e.g.,
optical/reflective, magnetic) to avoid excessive grinding. In addition, the centerless
grinding technique can utilize a CBN or diamond abrasive grinding wheel that is well
shaped and dressed to avoid grabbing the core wire 930, 1030, 1130 during the grinding
process.
[0084] The present invention should not be considered limited to the particular examples
described above, but rather should be understood to cover all aspects of the invention
as fairly set out in the attached claims. Various modifications, equivalent processes,
as well as numerous structures to which the present invention may be applicable will
be readily apparent to those of skill in the art to which the present invention is
directed upon review of the instant specification. It should be understood that this
disclosure is, in many respects, only illustrative. Changes may be made in details,
particularly in matters of shape, size, and arrangement of steps without exceeding
the scope of the invention. Additionally, alternative tip constructions including
a flexible coil tip, a polymer jacket tip, a tip including a coiled safety/shaping
wire, or combination thereof, and other such structure may be placed on the guidewire.
The scope of the invention is, of course, defined in the language in which the appended
claims are expressed.